Method for estimation of the quantity of fresh air present in the intake and exhaust manifolds of an internal combustion engine with a recirculation circuit
AssigneeMagneti Marelli Powertrain S.p.A.
InventorsGilberto Burgio, Alessandro Palazzi, Renzo Ruggiani, Mauro Suffritti
Life of this patent
Estimating the term…
Abstract
Method for estimation of the quantity of fresh air present in the intake and exhaust manifolds of an internal combustion engine with a recirculation circuit, by an observer, applied to a system of the third order, which models the physical system constituted by the intake and exhaust manifolds; the system is obtained from differential equations, which regulate the processes of mixing of the gases, and from an equation which represents the behavior of a lambda sensor.
Claims17
Method for estimation of the quantity of fresh air (maira, mairs) present in the intake and exhaust manifolds (3, 5) of an internal combustion engine (1) with a recirculation circuit (9, 10), by an observer (O) of the third order, applied to a system (S), which models the physical system constituted by the intake and exhaust manifolds (3, 5);
- the system (S) to be observed being obtained from differential equations, which regulate the processes of mixing of the gases, and from an equation which represents the behaviour of a lambda sensor (13);
- the state variables (x) of the said system (S) being a mass (maira) of fresh air which is present in the intake manifold (3), a mass (mairs) of fresh air which is present in the exhaust manifold (5) and a mass (mairlam) of fresh air equivalent to the oxygen reading carried out by a lambda sensor (13).
Method for estimation of the quantity of fresh air (maira, mairs) present in the intake and exhaust manifolds (3, 5) of an internal combustion engine (1) with a recirculation circuit (9, 10), by an observer (O), applied to a system (S), which models the physical system constituted by the intake and exhaust manifolds (3, 5);
- the system (S) to be observed being obtained from differential equations, which regulate the processes of mixing of the gases, and from an equation which represents the behaviour of a lambda sensor (13),
- wherein the said differential equations which regulate the processes of mixing of the gases are:
- { ⅆ m aira ⅆ t = ⅆ m thr ⅆ t · 1 + ⅆ m EGR ⅆ t · m airs m colls - ⅆ m eng ⅆ t · m aira m colla ⅆ m airs ⅆ t = ⅆ m eng ⅆ t · m aira m colls - ⅆ m fuel ⅆ t · A F stech - ⅆ m EGR ⅆ t · m aira m colls - ⅆ m out ⅆ t · m airs m colls [AutoLeftMatch]
- in which:
- maira is the mass of fresh air present in the intake manifold (3);
- mcolla is the overall mass of gas present in the intake manifold (3);
- mairs is the mass of fresh air present in the exhaust manifold (5);
- mcolls is the overall mass of gas present in the exhaust manifold (5);
- dmthr/dt is the flow rate of air supplied by a butterfly valve (7);
- dmEGR/dt is the flow rate of gas of the recirculation pipe (9);
- dmeng/dt is the flow rate of gas supplied to the cylinder (2);
- dmfuel/dt is the flow rate of fuel injected in the cylinder (2);
- AFstech is the stoichiometric ratio;
- and
- dmout/dt is the flow rate of gas in an exhaust pipe (8).
Method for estimation of the quantity of fresh air (maira, mairs) present in the intake and exhaust manifolds (3, 5) of an internal combustion engine (1) with a recirculation circuit (9, 10), by an observer (O), applied to a system (S), which models the physical system constituted by the intake and exhaust manifolds (3, 5);
- the system (S) to be observed being obtained from differential equations, which regulate the processes of mixing of the gases, and from an equation which represents the behavior of a lambda sensor (13),
- wherein the state variables (x) of said system (S) are a mass (maira) of fresh air which is present in the intake manifold (3), a mass (mairs) of fresh air which is present in the exhaust manifold (5) and a mass (mairlam) of fresh air equivalent to the oxygen reading carried out by a lambda sensor (13);
- the input variables (u) of said system (S) being a flow rate (dmthr/dt) of air supplied by a butterfly valve (7), and a flow rate (dmfuel/dt) of fuel injected in the cylinder (2);
- and the output variable (y) of said system (S) being a mass (moxylam) of oxygen, which is equivalent to the oxygen reading carried out by the lambda sensor (13), and
- wherein said system (S) of the third order to be observed is represented by the equations:
- { ⅆ x ⅆ t = A · x + B · u y = C · x [AutoLeftMatch]
- in which:
- x is a vector which represents the state variables of the system (S);
- y is a vector which represents the output variable of the system (S);
- u is a vector which represents the input variables of the system (S);
- A is the state matrix of the system (S);
- B is the matrix of the inputs of the system (S);
- and
- C is the matrix of the outputs of the system (S).
Method for estimation of the quantity of fresh air (maira, mairs) present in the intake and exhaust manifolds (3, 5) of an internal combustion engine (1) with a recirculation circuit (9, 10), by an observer (O), applied to a system (S), which models the physical system constituted by the intake and exhaust manifolds (3, 5);
- the system (S) to be observed being obtained from differential equations, which regulate the processes of mixing of the gases, and from an equation which represents the behavior of a lambda sensor (13),
- wherein the objectives of the flow rate of a recirculation valve (10) and of a butterfly valve (7) are expressed as a first objective flow rate (dmairtotobj/dt) of fresh air required in the cylinder (2), and as an objective ratio (EGR_EFF_OBJ) between a flow rate (dmEGR/dt) of gas in the recirculation pipe (9), and a flow rate (dmeng/dt) of gas supplied altogether to the cylinder (2), and
- wherein said first objective flow rate (dmairtotobj/dt), and said objective ratio (EGR_EFF_OBJ) are translated into a second objective flow rate (dmthrobj/dt) of air through a butterfly valve (7), and into a third objective flow rate (dmEGRobj/dt) of gas through a recirculation pipe (9), in order to control directly a butterfly valve (7) and a recirculation valve (10);
- this translation of the objectives is implemented by means of the following equations:
- ⅆ m EGRobj ⅆ t = ⅆ m airtotobj ⅆ t · EGR_EFF _OBJ 1 - ( 1 - % airs 100 ) · EGR_EFF _OBJ - k p · ( % airaobj - % aira ) % airaobj = EGR_EFF _OBJ + ⅆ m thr ⅆ t - ⅆ m EGR ⅆ t · ( 1 - % airs 100 ) ⅆ m thr ⅆ t + ⅆ m EGR ⅆ t ⅆ m throbj ⅆ t = ⅆ m EGRobj ⅆ t · 1 - EGR_EFF _OBJ EGR_EFF _OBJ
- wherein:
- EGR_EFF_OBJ is the said objective ratio;
- dmairtotobj/dt is the said first objective flow rate;
- dmthrobj/dt is the said second objective flow rate;
- dmEGRobj/dt is the said third objective flow rate;
- %aira is the percentage of fresh air present in the intake manifold (3);
- %airs is the percentage of fresh air present in the exhaust manifold (5);
- and
- %airobj is the objective of the percentage of fresh air present in the intake manifold (3).
Dependencies are inferred from the claim text.